For each anchor user, we discover a set of neighbors by estimating the distance with respect to all other users. As in LLORMA [1]}, we employ the arccos distance that is scaled in [0, 1]:
\(s = dist(a^{(j)}, u) = arccos \left(\frac{\mathbf {a}^{(j)} \cdot \mathbf {u}}{\Vert  \mathbf {a}^{(j)} \Vert  \cdot \Vert \mathbf {u}\Vert } \right),\) 
